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phpregexcurly-bracesmath-mode

Removing curly braces outside texs math-mode

I want to have curly braces removed outside texs math-mode. For example:

Lorem Ipsum $\mathbb{R}$ dolore. {Author} $\{1,\dotsc,n}$

should become:

Lorem Ipsum $\mathbb{R}$ dolore. Author $\{1,\dotsc,n}$

As you can't really negate regular expressions I was looking into look-aheads and -behinds. That wasn't working for me as technically speaking, {Author} also is between two dollar signs. Some regex professional having some advice for me?

I'd love to only use preg_replace when the problem isn't too complex for this.

Solution

  • You can use this lookahead based regex:

    $re = '/\$\\\w*{[^}]+}(*SKIP)(*F)|{[^}]*}/'; 
$str = "Lorem Ipsum \$\mathbb{R}\$ dolore. {Author} \${1,\dotsc,n}\$"; 

$result = preg_replace($re, '', $str);

//=> Lorem Ipsum $\mathbb{R}$ dolore.  Author $\{1,\dotsc,n}$

    RegEx Demo

    Here we are using PCRE verbs (*SKIP)(*F) to skip the math-mode blocks and replace { and } in rest of the text: